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Services Power Management Unit
Copyright © 12/13/06 Marvell
CONFIDENTIAL
Doc. No. MV-TBD-00 Rev. A
December 13, 2006
Document Classification: Proprietary Information
Page 179
Not approved by Document Control. For review only.
Services Power Management Unit
8
8.1
Overview
Chapter 6, “Services Clock Control Unit”
.
The slave power-management unit (BPMU) is responsible for the power-management and reset functions of the
application subsystem, including the application core, and the internal SRAM modules. Power states controlled
by the BPMU, referred to as D-states, are used to reduce the application subsystem power consumption (refer to
Power states controlled by the master power-management unit (MPMU) are referred to as S-states. Power states
of the core are referred to as C-states.
The slave clock-control unit (BCCU) is a divide-and-select unit that generates clocks needed by the applications
subsystem. The BCCU controls and uses basic clocks outputs from the services unit clock control unit (CCU).
shows the PXA300 processor clock and power-management architecture.
The four MPMU power states include:
•
S0 State — All internal power domains and external power supplies may be fully powered and functional. In
this mode, all internal clocks may be running. The application subsystem may be placed in D0, D1, or D2
power modes and is controlled by the BPMU.
•
S1 State — Not defined
•
S2 State — Entry into S2 state must be coordinated with the BPMU. Most internal power domains in the
application subsystem can be powered down, including the application core. All clock sources except to the
MPMU, BMPU, and real-time clock are disabled, and the external low-voltage power supplies (including
VCC_APPS) can be disabled. The remaining power domains are either powered down or placed in a
low-power state where state is retained but no activity is allowed. Recovery is through external and select
internal wake-up events, and recovery requires a system reboot to recover, because the program counter in
the application core is invalid.
•
S3 State — All external power supplies except VCC_BBATT can be powered down and all clock sources
except to the MPMU and real-time clock are disabled. Recovery is through external and select internal
wake-up events, and recovery requires a system reboot to recover, because the program counter in the
application core is invalid.
•
S4 State (Off) — In this state, all power supplies are powered down. The off state is exited when
VCC_BBATT is applied. Initially all internal power domains except PD_REG are powered down, all clocks
are not functional, and all resets are asserted. The MPMU and real-time clock are disabled. Recovery
requires an entire system reboot.
Figure 3-6
summarizes relationships between the MPMU power states (S0, S2, S3, and S4) and the BPMU
power states (D0, D1, D2 and D4). See
for a brief descriptions of the BPMU power states.